Seat arrangement and electrically powered wheelchair comprising the same

Abstract

The present disclosure relates to a seat arrangement ( 1 ) for an electrically powered wheelchair, wherein the seat arrangement comprises ( 1 ): a mounting arrangement for mounting the seat arrangement ( 1 ) to a chassis of an electrically powered wheelchair, a seat frame ( 3 ), a backrest frame ( 5 ), a backrest actuator ( 7 ), wherein the backrest frame ( 5 ) is pivotally coupled to the seat frame ( 3 ), forming a first pivot axis (A 1 ), and wherein the backrest frame ( 5 ) is pivotally coupled to the backrest actuator ( 7 ), forming a translatable second pivot axis (A 2 ), a retaining mechanism ( 11 ) arranged to retain the backrest frame ( 5 ) in an upright position while the backrest frame ( 5 ) is subjected to a forward-tilting force smaller than a threshold value, wherein the retaining mechanism ( 11 ) is arranged to allow movement of the backrest frame ( 5 ) to a forward-tilted position when the backrest frame ( 5 ) is subjected to a forward-tilting force equal to or greater than the threshold value, and a locking mechanism ( 13 ) arranged to lock the backrest frame ( 5 ) in the forward-tilted position. An electrically powered wheelchair comprising a seat arrangement is also disclosed herein.

The invention claimed is: 
     
       1. A seat arrangement for an electrically powered wheelchair, wherein the seat arrangement comprises:
 a mounting arrangement for mounting the seat arrangement to a chassis of an electrically powered wheelchair, 
 a seat frame, 
 a backrest frame, 
 a backrest actuator, 
 wherein the backrest frame is pivotally coupled to the seat frame, forming a first pivot axis, and wherein the backrest frame is pivotally coupled to the backrest actuator, forming a translatable second pivot axis, 
 a retaining mechanism arranged to retain the backrest frame in an upright position while the backrest frame is subjected to a forward-tilting force smaller than a threshold value, 
 wherein the retaining mechanism is arranged to allow movement of the backrest frame to a forward-tilted position when the backrest frame is subjected to a forward-tilting force equal to or greater than the threshold value, and 
 a locking mechanism arranged to lock the backrest frame in the forward-tilted position. 
 
     
     
       2. The seat arrangement of  claim 1 , wherein the retaining mechanism is arranged to retain the backrest actuator in a first position while the backrest frame is subjected to the forward-tilting force smaller than a threshold value, wherein the backrest frame is arranged to pivot about the first pivot axis and the second pivot axis to obtain a forward-tilted position when the backrest frame is subjected to a forward-tilting force equal to or greater than the threshold value, wherein the retaining mechanism is arranged to allow movement, corresponding to the translation of the second pivot axis, of the backrest actuator to a second position, and wherein the locking mechanism is arranged to lock the backrest actuator in the second position to thereby lock the backrest frame in the forward-tilted position. 
     
     
       3. The seat arrangement of  claim 1 , wherein the backrest frame is arranged to pivot about the first pivot axis and the second pivot axis to the forward-tilted position when an equilibrium state acting about the first pivot axis is broken by the forward-tilting force. 
     
     
       4. The seat arrangement of  claim 1 , comprising a backrest actuator bracket attached to the seat frame, wherein the backrest actuator is fixedly attached to the backrest actuator bracket. 
     
     
       5. The seat arrangement of  claim 4 , wherein the locking mechanism is arranged to lock the backrest actuator bracket relative to the seat frame to thereby lock the backrest actuator in the second position. 
     
     
       6. The seat arrangement of  claim 4 , comprising a first fastener, wherein the seat frame has a first seat frame through-opening and the backrest actuator bracket has a first backrest actuator bracket through-opening, wherein the first fastener is arranged in the first seat frame through-opening and in the first backrest actuator bracket through-opening. 
     
     
       7. The seat arrangement of  claim 6 , wherein the first fastener, the first seat frame through-opening and first backrest actuator bracket through-opening form the retaining mechanism. 
     
     
       8. The seat arrangement of  claim 6 , comprising a second fastener, wherein the seat frame has a second seat frame through-opening and the backrest actuation bracket has a first slotted backrest actuation bracket through-opening wherein the second fastener is arranged in the second seat frame through-opening and slidably arranged in the first backrest actuation bracket slotted through-opening. 
     
     
       9. The seat arrangement of  claim 8 , wherein the first fastener has a first mechanical strength and the second fastener has a second mechanical strength, wherein the second mechanical strength is higher than the first mechanical strength. 
     
     
       10. The seat arrangement of  claim 8 , comprising a third fastener, wherein the seat frame comprises a first seat frame slotted through-opening, and wherein the backrest actuator bracket comprises a second backrest actuator bracket through-opening, wherein the third fastener is arranged in the second backrest actuator bracket through-opening and slidably arranged in the first seat frame slotted through-opening. 
     
     
       11. The seat arrangement of  claim 6 , wherein the seat frame comprises a keyway and the backrest actuator bracket comprises a biased key which form the locking mechanism, wherein the first fastener is designed to break when the backrest frame is subjected to a forward-tilting force equal to or greater than the threshold value allowing sliding of the backrest actuator bracket relative to the seat frame, wherein the biased key is arranged to engage the keyway to lock the backrest actuator in the second position. 
     
     
       12. The seat arrangement of  claim 11 , wherein the locking mechanism comprises a leaf spring, wherein the key is biased by the leaf spring. 
     
     
       13. The seat arrangement of  claim 1 , wherein the backrest actuator comprises the retaining member and the locking member. 
     
     
       14. An electrically powered wheelchair comprising:
 a chassis, and 
 the seat arrangement of  claim 1  attached to the chassis.